The Critical Role of Carbon in the Chemical Delithiation Kinetics of LiFePO 4

Abstract

The chemical delithiation of LiFePO 4 has been carefully studied using two different types of LiFePO 4 : (1) carbon coated LiFePO 4 and (2) non-carbon coated LiFePO 4 . We have observed that only carbon coated LiFePO 4 can be successfully delithiated at room temperature using Na 2 S 2 O 8 as oxidizing agent. In order to unravel the role of carbon in the chemical delithiation process of non-carbon coated LiFePO 4 we have performed a systematic study using different carbon sources as well as different amount of extraneous carbon in the solution. The results obtained demonstrate that the addition of carbon is fundamental for the effective removal of lithium at room temperature, and only a very small amount of carbon of any nature is enough to achieve the successful chemical delithiation of non-carbon coated LiFePO 4 .